Weathering degradation

Denes, A.R. and Young, R.A. (1999). Reduction of weathering degradation of wood through plasma-polymer coating. Hol orschung, 53(6), 632-640. 

Varghese JK, Na SJ, Park JH, Woo D, Yang I, Lee BY (2010) Thermal and weathering degradation of poly (propylene carbonate). Polym Degrad Stab 95 1039-1044... 

Weathering degradation—sun, water, heat, wind Chemical reactions—oxidation, hydrolysis Mechanical—erosion... 

The increase in cellulose content of the weathered wood surface was shown by Browne (50) in work reported by Kalnins (26). Browne compiled analytical data on white pine wood that had been weathered outdoors for 20 years. Results showed that weathering degraded and solubilized lignin. Cellulose appeared to be considerably less affected, except in the top surface layer of the wood. Similar results were obtained with various kinds of wood exposed on a test fence for 30 years. The outer gray layer consistently exhibited very low lignin content (Table II). The lignin content of the brown layer immediately below this layer varied from 40 to 60% of that normally found for fresh nonexposed wood. The composition of inner wood layers only a few millimeters under the outer gray surface was similar to that of... 

Potential adverse effects embrittlement, weather degradation... 

Hamid SH, Amin MB, Maadhah AG. Weathering degradation of polyethylene. In Hamid SH, Amin MB, Maadhah AG, editors. Handbook of Polymer Degradation. New York Marcel Dekker 1995. 

Hamid HS et al. (1992) Weathering Degradation of Polyethylene. In Hanud SH et al. (eds) Handbook of Polymer Degradation. Marcel Dekker Inc., New York, Basel, Hong Kong, pp 219-260... 

To develop a laboratory-based weathering degradation model and examine it as applied to a real material in a real environment... 

DSC investigations of surface layers (Figure 5.87) show a loss in melt enthalpy and a reduction in melt temperature. Both effects indicate chemical degradation processes [622]. In the early stage of weathering, degradation may he correlated to an increase in crystalline content. Later, the degree of crystallization decreases and the spherulites are destroyed. 

The diversity of plastics products and, of course, the multitude of service conditions ask the certification of durability and the evaluation of properly modifications happened while they are in operation. The weathering degradation tests as well as the imposed functional requirements provide the useful and complementary considerations by which the stability studies are conducted. Unfortunately, the geographic criteria are not generally applicable, but they offer some guidelines by which the customers can select suitable materials. 

Fig. 14 Distribution of oxidation products in low-crystalline polypropylene exposed to weathering degradation, (open circle) outdoor oxidation, (open square) accelerated oxidation...

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